1. Field of the Invention
The present invention relates to a lead pin for a package substrate, and more particularly, to a lead pin for a package substrate that connects a package substrate on which an integrated circuit is mounted to a main board.
2. Description of the Related Art
With the development of electronics industry, semiconductor packages in various types have been manufactured. Recently, as the wiring density of a semiconductor package has been increased, a semiconductor package substrate of a Pin Grid Array (PGA) type in which a plurality of T-type lead pins are mounted has been widely used as a substrate that connects a package substrate on which an integrated circuit (IC) is mounted to a main board.
In a general package substrate, a pin insert type in which a pin is inserted through a hole and a T-type lead pin that is attached to a package substrate by a soldering have been mainly used. The T-type lead pin has gradually become widespread due to a limitation of the available area for the circuit configuration of the package substrate as compared to the pin insert type.
As the use of lead has been recently limited in consideration of environmental effects due to soldering, a solder (Sn—Ag—Cu, and Sn—Sb) not using lead has been used, such that the melting temperature of the solder is increased.
At this time, as the melting temperature of the soldering is high, solder for connecting lead pins that support lead pins is melted by reflow heat during a reflow process for mounting an IC chip on a package substrate, thereby causing an inclination of the lead pins.
In addition, defects frequently occur, such as in the case that solder paste overflows toward the upper portions of the lead pins during the reflow process so as to be spread to connection pins and the like. Therefore, there is a demand for techniques capable of solving these problems.